As this type of electromagnetic clutch, an electromagnetic clutch disclosed in Patent Document 1 is known as an example. The electromagnetic clutch disclosed in Patent Document 1 includes: a ring-shaped yoke in which an electromagnetic coil is fixed by a resin material; and an insulation case fixed to the back of the yoke by caulking. Lead wires for supplying power and the ends of the electromagnetic coil are connected by terminal members in the insulation case, and the insulation case is filled with a resin material to make these connected parts waterproof.